Heart disease is a significant health problem which has been the subject of substantial medical study. Bypass surgery has become commonplace; yet such surgery may be unavailable to many patients, either because of the nature of the occlusions or the physical condition of the patient.
One promising alternative technique for treating such cases is known as trans-myocardial revascularization (TMR). Although this technique was considered as early as the work of Dr. C. Beck "the Development of a New Blood Supply to the Heart By Operation", Annals of Surgery, Vol. 102, No. 5 (11/35) pp. 801-813, the method was not extensively studied until the work of Dr. M. Mirhoseini and M. Cayton, an example of which is found in "Lasers in Cardiothoracic Surgery" in Lasers in General Surgery (Williams and Williams; 1989) pp. 216-223.
An early device to perform TMR is described in Aita et al., U.S. Pat. No. 5,380,316, issued Jan. 10, 1995. In the procedure described in that patent, a number of channels are formed through the myocardium between the ventricle and the exterior of the heart through the epicardium and myocardium by means of a laser apparatus. These channels were approximately 1.5 mm-2.0 mm in diameter and approximately 1 to 3 cm deep. Clinical tests have demonstrated that such channels facilitate revascularization of the heart muscle and recovery of heart function.
Unfortunately, this technique has some attendant difficulties. The laser equipment for performing such procedures is large and expensive and may be unavailable to smaller and more remote medical facilities. Some patients may therefore find it difficult to gain access to a properly equipped medical facility when treatment is needed.
One alternative to the use of lasers would be to use a mechanical cutter to produce the channels. Unfortunately, as noted in the Aita et al. patent, prior art methods of mechanical piercing and cutting of the heart wall produce tearing of the tissue. Such tearing leads to fibrosis, which combined with the problems of maintaining clear, clean channels, seriously diminishes the effectiveness of the TMR treatment produced by such methods. Hence, such prior art mechanical piercing does not adequately facilitate rapid and clean healing of channels.
Another alternative approach, melting of the myocardium by hot probes, has proven unsatisfactory, partly because there is no mechanism for removal of melted material from the channel.
It would therefore be desirable to produce clear, clean channels using relatively inexpensive and easily transportable systems, which may be deployed in remote locations.